1. Field of the Invention
The present invention relates in general to a seat slide device for a motor vehicle, and more particularly, to a method of assembling the seat slide device.
2. Description of the Prior Art
In order to provide a seat occupant with a comfortable sitting posture, various types of seat slide devices have been proposed and put into practical use particularly in the field of motor vehicles.
One of the conventional seat slide devices is shown in FIG. 12 of the accompanying drawings, which generally comprises a lower rail 101 secured to a vehicle floor (not shown), an upper rail 103 slidably disposed on the lower rail 101 and secured to a bottom of a seat (not shown), and a lock mechanism (not shown) for locking the upper rail 103 at a desired fore-and-aft position relative to the lower rail 101. As is seen from FIG. 12, the lower rail 101 has a generally "U"-shaped cross section and thus has outwardly extending side flanges (no numerals), while the upper rail 103 has a generally "C"-shaped cross section and thus has inwardly extending side flanges (no numerals), and these two rails 101 and 103 are coupled with their side flanges facing each other. Guide rollers 105 are interposed between respective major parts of the lower and upper rails 101 and 103, and balls 107 are disposed between the facing flanges of the rails 101 and 103. These guide rollers 105 and the balls 107 are held by axially spaced two retainers 109 (only one is shown) which are arranged between the lower and upper rails 101 and 103, as shown. With this arrangement, the upper rail 103 on which the seat is mounted is slidable forward or rearward relative to the fixed lower rail 101. When the upper rail 103 comes to a desired position, the lock mechanism is operated to lock the upper rail 103 at the desired position.
However, the above-mentioned seat slide device tends to have the following drawbacks due to its inherent construction.
That is, it is difficult or at least troublesome to assemble the seat slide device with precision. More specifically, it has been difficult to provide the spaces for the guide roller 105 and the balls 107 with precise dimensions "A" and "B" due to unavoidable difficulty in producing the rails 101 and 103 by press or roll forming method. In fact, if the dimensions "b" and "a" of the lower and upper rails 101 and 103 lack accuracy, the dimensions "A" and "B" of the spaces for the guide roller 105 and the balls 107 lack accuracy and thus smooth sliding movement of the upper rail 103 relative to the lower rail 101 is not achieved. In a severe case wherein the dimension error exceeds allowance, it becomes impossible to mount the guide roller 105 and the balls 107 into the spaces.